Multiplex control system for memory seat or the like load

Abstract

An improved control system is provided for controlling the variable characteristic associated with automotive peripheral devices, such as seats, mirrors, seat bladders or the like, having a 'memory' capability. The control system avoids overloading a central controller and/or a data link between the central controller and the device being controlled, by approximating the 'run' interval required to vary the relevant characteristic, i.e. seat position, from its present value to a target value recalled from memory. Pulses are generated by variations in the seat position and accumulated in a counter which may be separate from the central controller. At the completion of a 'run' for the approximated interval, the accumulated count is used to update a count representative of the 'present' seat position. The updated position is again compared to the target position and, if it differs by more than some acceptable tolerance, a new interval is determined and is 'run'. Provision may be made to compensate the determination of the interval for changes in the rate at which the seat responds.